Theresa May should walk away from the EU without a deal instead of showing "weakness" by tying Britain to the Customs Union beyond 2021, the Democratic Unionist Party, has warned.

Sammy Wilson, the DUP’s Brexit spokesman, also criticised “geriatric” members of the House of Lords for trying to weaken Government legislation to take Britain out of the European Union with 15 amendments.

Mr Wilson was speaking after The Daily Telegraph disclosed that the Government will tell Brussels it is prepared to stay tied to the customs union beyond 2021.

Mr Wilson – whose party’s MPs are keeping Mrs May's Conservative Government in power - told Chopper’s Brexit Podcast today: “I don't believe it is necessary for us to stay in beyond that period. In doing so the PM shows a sign of weakness to EU negotiators - if they stick their heels in, she will concede.

“When the PM has stuck her heels in, as she did in December, they changed the agreement. As she did in March, when they said they wouldn't accept the legal agreement, they backed down.

“She should learn from that. Stand up to them. They need the deal, they will back down. Do this kind of thing where you sway with the wind you will come off worse.”

On the House of Lords’ amendments Mr Wilson – who was debating Brexit on the Podcast with Labour MP Ian Murray - said the Government should seek to reverse them all in the House of Commons.

He said: “They not experts. They are a bunch of geriatric members, most of whom are on the EU payroll. You expect them to vote the way they have done.”

Also on the podcast, Hilary McGrady, the new director general of the National Trust, said the Trust is willing to forego millions of pounds in EU subsidies to improve the UK’s natural environment.

She said: “We may well take a financial hit as an organisation on the back of this but that is good, we are cool with that because that means we will get benefits for nature and that is what the charity is here to do.”

Kemi Badenoch, the Conservative party’s vice chairman for candidates, also said that parliamentary hopefuls should consider deleting their Twitter feeds.

Ms Badenoch has written to Conservative candidates who have applied to stand in the 2022 general election to say that their social media accounts are now “fair game” for their opponents.

Ms Badenoch - who became a vice chairman in January - told Chopper’s Brexit Podcast that it was not “bad advice” for candidates to delete their social media history as soon as they are selected.

She said: “I have already sent advice to candidates and what I have said was ‘be aware that your social media profile is now fair game, you can’t expect people not to take it into account. Think about what you say and how you say it when you use social media’.

“If you are unable to control yourself, then delete your account might be the advice that I give - but you have to look at it almost as if it is the real world now.”